SharePoint Workflow Completes At Wrong Step

I have a SharePoint 2010 workflow that I want to work this way:

Jenny completes a form and assigns it to Bob.  Bob takes action on the form by editing it and reassigns it to Jenny.  Jenny gets an email telling her it was complete.

Here's the actual workflow:

If CurrentItem:Assigned To equals Smith, Bob

           Email bob.smith@email.com

then Wait for Assigned To to equal James, Jenny

then Email jenny.james@email.com

However the workflow only sends an email to Bob and then shows that it has complete.  How do I get the workflow to pause and then act on the 2nd part?  Do I need 2 workflows?